Fault Phenomenon: Volvo L90 wheel loader low transmission oil pressure, poor shift quality, instrument indicates filter clogged.

Troubleshooting Process:
– Checked filter: transmission oil filter clogged with friction material powder.
– Checked oil quality: oil blackened with burnt smell.
– Checked bypass valve: bypass valve opened.
– Checked clutches: clutch discs abnormally worn.

Root Cause: Abnormal wear of the transmission clutch discs generated a large amount of powder, quickly clogging the oil filter and causing low oil pressure.

Required Parts: Replace transmission oil filter and fluid, inspect clutch disc wear condition.